Long story short, the economy redemptions are almost never worth it. In your case, for example, you could spend 80k miles on the $1,500 eco roundtrip or 80k miles on the $4,200 one way. (Keeping in mind, of course, the $500 in taxes and fees that'd probably be added to a reward reservation for this itinerary.)

My advice: you say you're Flying Blue Silver. That means you can buy unlimited miles. I'd look for a flight with roundtrip business class award inventory and revenue economy inventory at a reasonable price. I'd call FB and ask them to give you a courtesy three-day hold on the business class ticket, then I'd book the economy ticket; I'd check vayama.com for good deals, as well. I'd then buy the 60k miles I need for about $2,000, which is much cheaper than the $4,200 for a one-way flight, call back FB and buy my reservation for an all-in price for the two tickets of about $3,500. Much better than the $10k for a cash reservation.

Of course, if you have American Express MR points, I believe you can still transfer those. If you don't have a Platinum card, there's an ongoing 50k promotion with the Benz-branded AmEx Platinum card if you spend $1k in the first three months. mbfs.com/MBcard It'd take until the end of the billing cycle for the MR points to appear, and another few days to transfer the points to Flying Blue.

Another thing to look out for are the Promo @Awards for Flying Blue. http://www.flyingbluenews.com/promot...omoawards.html It doesn't seem like they currently have what you're looking for, but if you find an IAH-Europe 1/2/3 and a Europe 1/2/3-NBO award on that list, you could get the business class roundtrip for 100k miles instead of 160k.

Good luck! Let us know how things turn out.